This invention relates to pressure-responsive apparatus.
Pressure-responsive apparatus commonly relies on the detection of displacement of an elastic or resilient member subjected to pressure, such as, for example, a diaphragm of a pressure capsule. Difficulties have been experienced in the past in making accurate measurements of pressure in regions subject to large temperature changes, such as, for example, in gas-turbine engines (where the temperature may range from the order of four hundred degrees Centigrade to minus fifty degrees Centigrade), since the Young's modulus of elasticity of the elastic member (which determines the amount of deformation of the member produced upon application of pressure to it) may greatly vary in accordance with temperature. Further difficulties are experienced in gas-turbine engines since the transducer used in the apparatus for sensing pressure within the engine must remain unaffected by high vibration levels and a large number of contaminants, such as, for example, fuel, hydraulic fluids and lubricants, that may be present. In gas-turbine engines used in aircraft the pressure-responsive apparatus must moreover be of a compact size and low weight.